Typically, when one computer or computer program communicates with another, then the two entities exchange messages. To enable message interpretation, an agreed format is often used. One such format is the standard eXtensible MarkUp Language (XML) format, although other standards as well as proprietary formats are also used.
The format generally identifies specific non-content tags or elements which identify the function or interpretation of the information contained within the tags or elements. The recipient of such messages typically uses the tags or elements to parse the incoming message and thereby extract the data part or information content of the message.
In practice, using such formatting provides great flexibility, not least because a message effectively carries with it sufficient information to allow for whatever processing needs to be done to extract the actual message content. However, the disadvantage is that the messages increase in size with content in the form of the formatting. This may detrimentally affect performance in terms of message throughput and communication link bandwidth.